Could not change permission for files under /boot/efi

Issue

• Could not change permission for /boot/efi/EFI/redhat/grub.conf on RHEL 6:

  [root@rhel6 redhat]# ls -ltr
  total 248
  -rwx------ 1 root root 247570 Jan 22  2011 grub.efi
  -rwx------ 1 root root    887 May 20  2014 grub.conf
  
  [root@rhel6 redhat]# pwd
  /boot/efi/EFI/redhat
  
  [root@rhel6 redhat]# chmod 600 grub.conf
  
  [root@rhel6 redhat]# ls -ltr
  total 248
  -rwx------ 1 root root 247570 Jan 22  2011 grub.efi
  -rwx------ 1 root root    887 May 20  2014 grub.conf
  

• Could not change permission for /boot/efi/EFI/redhat/grub.cfg on RHEL 7 and above:

  [root@rhel8 ~]# cd /boot/efi/EFI/redhat/
  
  [root@rhel8 redhat]# ls -ltr
  total 4884
  -rwx------. 1 root root 2285512 Feb 25  2021 grubx64.efi
  drwx------. 2 root root    4096 Feb 25  2021 fonts
  -rwx------. 1 root root  918944 Apr  7  2021 shimx64-redhat.efi
  -rwx------. 1 root root  924888 Apr  7  2021 shimx64.efi
  -rwx------. 1 root root  846856 Apr  7  2021 mmx64.efi
  -rwx------. 1 root root     182 Apr  7  2021 BOOTX64.CSV
  -rwx------. 1 root root    1024 Jan 26 11:33 grubenv
  -rwx------. 1 root root    6374 Jan 26 11:33 grub.cfg
  
  [root@rhel8 redhat]# pwd
  /boot/efi/EFI/redhat
  
  [root@rhel8 redhat]# chmod 600 grub.cfg
  
  [root@rhel8 redhat]# ls -ltr
  total 4884
  -rwx------. 1 root root 2285512 Feb 25  2021 grubx64.efi
  drwx------. 2 root root    4096 Feb 25  2021 fonts
  -rwx------. 1 root root  918944 Apr  7  2021 shimx64-redhat.efi
  -rwx------. 1 root root  924888 Apr  7  2021 shimx64.efi
  -rwx------. 1 root root  846856 Apr  7  2021 mmx64.efi
  -rwx------. 1 root root     182 Apr  7  2021 BOOTX64.CSV
  -rwx------. 1 root root    1024 Jan 26 11:33 grubenv
  -rwx------. 1 root root    6374 Jan 26 11:33 grub.cfg